Reusable Container and Method for Retorting Flexible Packages Containing Foodstuff

ABSTRACT

Method for retorting flexible packages containing foodstuff comprising retorting the flexible packages containing foodstuff in reusable, hermetically resealable, rigid retort containers. A retort container comprises a body portion including a base and outer side walls extending from the base to a mouth portion defining an opening and a resealable lid for selectively hermetically sealing the opening in the container and alternatively opening the container for removal of the flexible packages containing foodstuff.

TECHNICAL FIELD

This invention relates to retorting packaged foodstuff, and in particular, relates to retorting flexible packages containing foodstuff.

BACKGROUND OF THE INVENTION

Packaged food products, also called foodstuffs, often must be sterilized. One process for sterilizing packaged foodstuff is retorting, which is treatment of the packaged foodstuff under heat and pressure. Generally, in a retort system, a foodstuff is packaged in suitable containers such as cans, glass jars, plastic trays, or flexible pouches. The packaged foodstuff is then subjected to heat and pressure in a processing chamber.

Some retort systems are batch processes and some are continuous processes. Continuous processes are often more efficient. Examples of retort systems include continuous hydrostatic retort systems and continuous agitating retort systems. Both types of systems include a conveyor for carrying foodstuff packaged in containers, a container feeder for delivering packaged foodstuff to the conveyor, a retort chamber for treating the packaged foodstuff with elevated temperature and pressure, and a discharge system for discharging the retorted packaged foodstuff for further packaging and handling. The hydrostatic retort systems include water columns for maintaining elevated pressure in the retort chamber and agitating retort systems include agitators for agitating the foodstuff within its container as the packaged foodstuff travels through the retort system. Such continuous retort systems are often large and expensive and require a large capital investment for the packaged foodstuff manufacturer.

Traditionally, a retort container of choice for packaging foodstuff and retorting the packaged foodstuff is the metal can. The foodstuff is packaged in the can and retorted in the can and then the can also serves as packaging for presentation to the consumer. Continuous retort systems are conventionally tailored to the particular type and size of retort container. Thus, a continuous retort system for cans is particularly suited for cans and cannot be easily or inexpensively modified to handle other retort containers such as glass jars, plastic trays, or flexible pouches. Conventionally, a packaged foodstuff manufacturer must have separate continuous retort systems for different types of retort containers such as cans and flexible pouches.

Flexible packaging such as pouches made of plastic film, metal foil, or a laminate of plastic film and metal foil are commonly used for packaging foodstuff because the cost of flexible packaging is typically less than the cost of cans and other types of packaging. Nonetheless, packaged foodstuff manufacturers find it difficult to switch from flexible packaging for retorted packaged foodstuff because the continuous retort systems that they already own are not suitable for retorting flexible packaging and the capital investment in converting continuous retort systems from using cans as retort containers to flexible packaging as retort containers or purchasing an additional system custom made for retorting foodstuff packaged in flexible packaging is too expensive. Foodstuff packaged in flexible packaging typically requires retorting in a closed chamber with overhead pressure sufficient to equalize the pressure inside and outside of flexible package so that the flexible package does not burst. The conventional method of retorting flexible packaging to accommodate the equalization of pressure is by loading the flexible packaging onto racks and retorting the flexible packages in pressurized chambers in batches, rather than continuously as with cans. Such batch processes require more handling and are more labor intensive than with processing with cans. Batch processing is also typically much slower than continuous processing. Thus, with conventional systems, the cost of retorting foodstuff packaged in flexible packages is excessive when compared to packaging foodstuff in cans with existing equipment.

Thus, there is a need for an effective and economical method of retorting foodstuff packaged in flexible packaging.

SUMMARY OF THE INVENTION

This invention addresses the foregoing need by providing a method for retorting flexible packages containing foodstuff comprising retorting the flexible packages containing foodstuff in reusable, hermetically resealable, rigid retort containers. According to one embodiment of the invention, such a retort container is suitable for use in existing conventional retort equipment without substantial modification of the equipment.

More particularly, according to an embodiment of the invention, a method for retorting flexible packages containing foodstuff comprises placing the flexible packages containing foodstuff into reusable, hermetically resealable, rigid retort containers, hermetically sealing the flexible packages containing foodstuff in the retort containers, retorting the flexible packages containing foodstuff in the containers, and opening the containers and removing the retorted flexible packages containing foodstuff from the containers. The system reduces packaging costs because it can be adapted to existing retort equipment and it uses flexible packaging which is typically less expensive than other types of packaging such as cans. According to a preferred embodiment, the step of retorting the flexible packages containing foodstuff is continuous and the method further comprises reusing the retort containers. In a more preferred embodiment, the steps of placing, hermetically sealing, retorting, opening, and removing are continuous. Furthermore, because flexible foodstuff packaged in flexible packaging can be formed into a thinner overall configuration than cans, foodstuff packaged in flexible packages can be thoroughly heated and sterilized or cooked faster than foodstuff packaged in cans. In addition, with flexible packaging, the foodstuff near the exterior of the container is less likely to be overcooked in order to be thoroughly sterilize the center of the foodstuff in the packaging.

According to another embodiment, a reusable, hermetically resealable, rigid retort container for retorting flexible packages containing foodstuff is provided and comprises a body portion including a base and outer sidewalls extending from the base to a mouth portion defining an opening and a resealable lid for selectively hermetically sealing the opening in the container and alternatively opening the container for removable of the flexible packages containing foodstuff. Such a reusable retort container is useful for retorting flexible packages containing foodstuff in existing conventional retort equipment without substantial modification of the equipment.

Other embodiments of the invention are explained and illustrated in the following detailed description of embodiments, drawings, and claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a reusable retort container made in accordance with the present invention.

FIG. 2 is a perspective view of a foodstuff packaged in a flexible pouch for use with an embodiment of this invention.

FIG. 3 is a schematic diagram of a system for retorting flexible packages containing foodstuff, in accordance with an embodiment of this invention.

FIGS. 4A-4D are perspective views of the filling and sealing of the container shown in FIG. 1.

FIGS. 5A and 5B are perspective views of an alternative clam shell retort container made in accordance with an embodiment of the present invention.

FIGS. 6A and 6B are an exploded perspective view and a sectional perspective view of a retort container made in accordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

As summarized above, this invention encompasses a method for retorting flexible packages containing foodstuff and a reusable, hermetically resealable, rigid retort container for retorting flexible packages containing foodstuff. Embodiments of the method and container of this invention are described in detail below. An embodiment of this invention is particularly useful for retrofitting existing conventional continuous retort systems normally configured for retorting canned foodstuff such that the same system can be used to retort foodstuff packaged in flexible packages such as flexible pouches. Such an embodiment provides a relatively inexpensive method of retorting foodstuff packaged in flexible packages because a custom reconfiguration of the retort system or the purchase of a new custom retort system for flexible packaging is avoided.

Turning to FIGS. 1 and 2, a retort container 10 and a flexible pouch filled with foodstuff in accordance with an embodiment of this invention are shown. The retort container 10 comprises a cylindrical body portion 14 and a threaded lid 16. The body portion 14 comprises a base 18 and outer side walls 20 extending from the base to a threaded mouth 22 defining an opening 24 in the base. The base 18 and outer side walls 20 define a void 26 in the body portion 14 of the retort container 10 for receiving one or more of the flexible pouches 12.

The threaded lid 16 of the retort container 10 is circular in shape and has a square central recess 28 for receiving a closure tool (not shown) which manipulates the lid 16 and selectively hermetically seals the opening in the container and alternatively opens the container for removable of the flexible pouches 12 containing foodstuff. If necessary for a hermetic seal, the lid can include a gasket or o-ring or the like about its periphery. To seal lid 16 to the mouth 22 of the body portion 14, the threads of the lid and body portion mouth are engaged and the lid is twisted onto the body portion. Although the mechanism in FIG. 1 for sealing the lid 16 to the body portion 14 of the retort container 10 is a threaded seal, the lid can be sealed to the container in other ways such as with a clamp or the like.

The configuration of the retort container 10 illustrated in FIG. 1 is a cylindrical canister and is therefore useful in retrofitting existing retort systems used for foodstuff packaged in cans. Although the retort container 10 illustrated in FIG. 1 is a canister, it should be understood that retort containers useful in the present invention can be made in a variety of other configurations suitable for the particular application or retrofit as would be understood to those skilled in the art from this specification.

The flexible pouch 12 illustrated in FIG. 2 comprises a foodstuff disposed in flexible plastic film and sealed at its ends by heat seals 32. Such a flexible pouch is well known to those skilled in the art. It should be understood to those skilled in the art that the flexible containers suitable for use with embodiments of this invention can have a variety of configurations and can be made from a variety of flexible materials. Suitable materials for making such flexible pouches should be suitable for packaging foodstuffs and withstand the elevated temperatures of retorting. Examples of such materials include polymer films, metal foils, and laminates of polymer films and metal foils.

A continuous system 38 for retorting flexible packages containing foodstuff in accordance with an embodiment of this invention is illustrated in FIG. 3. Flexible packages containing foodstuff such as the flexible pouch 12 illustrated in FIG. 2 are made at a conventional continuous form-fill-seal station 40. The structure and operation of form fill seal systems for packaging foodstuffs in flexible packages are well known to those skilled in the art and are not described here in detail.

The flexible packages containing foodstuff are conveyed from the form-fill-seal station 40 to a continuous retort container loading station 42 at which the flexible packages 12 containing foodstuff are placed in the void 26 inside the body portion 14 of the retort container 10. The number of flexible packages 12 containing foodstuff placed in the retort container 10 depends on the relative size of the packages and the containers, but the flexible container desirably fills as much of the void in the container as possible without interfering with closing the lid 16 on the body portion 14.

The retort containers 10 containing the flexible containers 12 or pouches are then conveyed to a continuous water filling station 44 wherein the void 26 inside the body portion 14 of the containers is substantially entirely filled with water. The water prevents expansion of the flexible pouches inside the containers 10 during retorting. Although the containers 10 do not have to be completely filled with water, they are desirably filled as full as possible without interfering with the seal formed by closing the lid 16.

After filling the remaining void in the retort containers 10 with water, the containers are conveyed to a continuous sealing station 48 at which the respective lids 16 of the containers 10 are automatically and continuously threaded onto the mouth 22 of the outer side walls 20 of the containers to form a hermetic seal so that the containers are airtight.

FIGS. 4A-4D also illustrate filling the containers 10 with flexible packages 12 of foodstuff and water and sealing the containers. FIGS. 4A and 4B illustrate placement of a flexible pouch containing foodstuff 12 in a container 10. FIG. 4C illustrates filling the remaining void in the container 10 with a water spray nozzle 46. FIG. 4D illustrates the sealing of the container body portion 14 with the lid 16.

The container loading station 42, water filling station 44, and container sealing station 48 are not described in further detail as their detailed structure is within the skill of one of ordinary skill in the art in combination with the specification.

After the containers 10 are sealed at the sealing station 48, the containers are conveyed to a conventional continuous retort system 50 normally configured for retorting foodstuff packaged in cans. Such a system includes a container feeder 52 for feeding the sealed containers 10 into a retort chamber 54 in which the containers and the flexible packages 12 containing foodstuff are subjected to sufficient heat under pressure to sterilize the flexible package and the foodstuff contained therein. The sealed containers 10 are then conveyed from the retort chamber 54 to a continuous container discharge station 56 at which the containers are automatically and continuously opened by unscrewing the lids 16 from the body portion 14 of the containers and the water and retorted flexible package containing foodstuff are dumped from the containers onto a conveyor. This conveyor conveys the retorted flexible packages containing foodstuff to a secondary packaging station 58 for conventional labeling and packaging of the flexible packages for shipment and distribution. Water dumped from the containers 10 at the discharge station 56 is recovered and returned to the water filling station 44 via a water recycle system 60 and used containers 10 are returned to the container loading station 42 via a container recycle container conveyor 62.

Further details of the container discharge system 56, the secondary packaging station, the water recycle system 60, and the container recycle conveyor 62 are not disclosed in further detail because such details would be understood to those skilled in the art after reading this specification. Although the continuous system 38 in FIG. 3 for retorting flexible packages is described as continuous, the container of this invention can also be employed to advantage in batch systems.

An alternative embodiment of a container 68 having a clam shell configuration is illustrated in FIGS. 5A and 5B. This clam shell retort container 68 comprises first and second clam shells 70 and 72 in the shape of half cylinders and connected to one another with hinges 74. One or more flexible packages 12 containing foodstuff are placed in the clam shell halves 70 and 72 and the clam shells are closed together and sealed with a mechanism such as a clamp 78 or the like. The seal can be enhanced by known sealing means such as a gasket.

Still another alternative embodiment of a retort container 80 having a doughnut shape is illustrated in FIGS. 6A and 6B. This retort container 80 comprises a body portion 82 and a lid 84 for hermetically sealing the retort container. The body portion 82 comprises a doughnut shaped base 86 having a circular outer periphery 88 and a concentric opening 90. Outer side walls 92 extend from the outer periphery 88 of the base 86 to a mouth 94 which defines an opening 96 in the body portion 82. An inner wall 98 inside of and spaced from the outer side walls 92 extends from the concentric opening 90 in the base 86 to an opening 100 proximate the mouth 94 of the container 80 and forms an open flow passageway 101 through the retort container 80 from the base 86 through the lid 84.

The lid 84 comprises a doughnut shaped disc 102 having a threaded mouth 104 defining a concentric opening 106 in the lid. The doughnut shaped disc extends from the mouth 104 to an outer periphery 108. A sealing material such as a gasket or o-ring 110 is disposed about the outer periphery 108 of the lid.

The retort container 80 illustrated in FIGS. 6A and 6B is used in the same manner as the retort containers 10 and 68 illustrated in FIGS. 1 and 5A and 5B. The doughnut shaped retort container 80, however, provides for heat transfer during retorting through both the outer side walls 92 and inner wall 98 for quicker heating of the flexible packages inside the container. During retorting, heating media such as steam, air, or water flows through the open passageway 101 formed by the inner wall 98.

While the invention has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the invention should be assessed as that of the appended claims and any equivalents thereof. 

1. Method for retorting flexible packages containing foodstuff comprising: placing the flexible packages containing foodstuff into reusable, hermetically resealable, rigid retort containers; hermetically sealing the flexible packages containing foodstuff in the retort containers; retorting the flexible packages containing foodstuff in the containers; opening the containers; and removing the retorted flexible packages containing foodstuff from the containers.
 2. Method as in claim 1 wherein the step of retorting is continuous and the method further comprises reusing the containers.
 3. Method as in claim 1 wherein the steps of placing, hermetically sealing, retorting, opening, and removing are continuous and the method further comprises reusing the containers.
 4. Method as in claim 1 wherein the step of retorting comprises hydrostatic retorting.
 5. Method as in claim 1 wherein the step of retorting comprises agitating retorting.
 6. Method as in claim 1 wherein the containers have avoid inside and the step of placing the flexible packages containing foodstuff into the containers comprises placing the flexible packages containing foodstuff in the void, the method further comprising the step of filling with water at least a portion of any void in the containers remaining after placing the flexible packages containing foodstuff.
 7. Method as in claim 6 wherein the step of filling with water comprises filling with water substantially the entire void remaining in the containers.
 8. Method as in claim 1 wherein the retort containers comprise: a body portion including a base and outer side walls extending from the base to a mouth portion defining an opening; and a resealable lid for selectively hermetically sealing the opening in the container and alternatively opening the container for removal of the flexible packages containing foodstuff.
 9. Method as in claim 8 wherein the containers are canisters.
 10. Method as in claim 9 wherein the canisters are substantially cylindrical.
 11. Method as in claim 8 wherein: the container body comprises an inner wall inside and spaced from the outer side wall and extending from an opening in the base to an opening proximate the mouth of the container to form an open passageway for allowing flow of a heating medium through the passageway; and the lid has a mouth defining an opening for receiving the inner wall and hermetically sealing the lid to the inner wall when the lid is sealed to the container body.
 12. Method as in claim 11 wherein the containers are substantially cylindrical canisters, the void inside the container body between the outer side wall and inner side wall is annular, and the passageway is annular.
 13. Method as in claim 12 wherein the lid mouth and inner wall are threaded such that the lid mouth is threaded onto the inner wall when the lid is hermetically sealed to the container body.
 14. Method as in claim 13 wherein the lid has a periphery and comprises an o-ring seal about the periphery for hermetically sealing the lid to the container body.
 15. Method as in claim 1 wherein the containers comprises first and second clam shell halves which are selectively hermetically sealable to one another and alternatively separable for opening the container for removal of the flexible packages containing foodstuff.
 16. Method as in claim 1 wherein the flexible packages containing foodstuff comprise foodstuff packaged in flexible pouches.
 17. Method as in claim 16 wherein the pouches comprise polymer film, metal foil, or a polymer film/metal foil laminate.
 18. A reusable, hermetically resealable, rigid retort container for retorting flexible packages containing foodstuff comprising: a body portion including a base and outer side walls extending from the base to a mouth portion defining an opening; and a resealable lid for selectively hermetically sealing the opening in the container and alternatively opening the container for removal of the flexible packages containing foodstuff.
 19. Retort container as in claim 18 wherein the containers are canisters.
 20. Retort container as in claim 18 wherein: the container body comprises an inner wall inside and spaced from the outer side wall and extending from an opening in the base to an opening proximate the mouth of the container to form an open passageway for allowing flow of a heating medium through the passageway; and the lid has a mouth defining an opening for receiving the inner wall and hermetically sealing the lid to the inner wall when the lid is sealed to the container body.
 21. Retort container as in claim 20 wherein the containers are substantially cylindrical canisters, the void inside the container body between the outer side wall and inner side wall is annular, and the passageway is annular.
 22. Retort container as in claim 21 wherein the lid mouth and inner wall are threaded such that the lid mouth is threaded onto the inner wall when the lid is hermetically sealed to the container body.
 23. Retort container as in claim 22 wherein the lid has a periphery and comprises an o-ring seal about the periphery for hermetically sealing the lid to the container body.
 24. A reusable, hermetically resealable, rigid retort container for retorting flexible packages containing foodstuff comprising first and second clam shell halves which are selectively hermetically sealable to one another and alternatively separable for opening the container for removal of the flexible packages containing foodstuff. 